The infant size Jarvik 2000 heart is the smallest permanently implantable blood pump developed as part of the NIH Pediatric VAD Program, and to our knowledge, the smallest in the world. At only 10.5mm diameter, 5.2 cm long and 4cc in volume it is small enough to implant in the ventricular apex of 3.5 Kg. newborns yet it has flow capacity over 3L/min - sufficient output for children up to 25 Kg. Animal implants have shown that the pump remains free of thrombus and operates at low power without causing hemolysis. The pump represents a completed design, incorporating all of the requirements for a long term implant, including welded hermetic sealing of the motor stator and rotor magnet, miniature hermetic feed-throughs for the power cables, a very long life ceramic conical bearing design, and pacemaker type high flex life power cables from the external controller to the implanted blood pump. An advanced microprocessor based control system has just been completed, although only the software for the basic functions (speed setting, measured speed, battery remaining, power, display function management via membrane switches) is presently available. This permits basic operation but does not yet implement some of the more advanced functions planned for the future. Jarvik Heart, Inc. is a small company of only 36 employees, but has successfully conducted clinical trials with the adult model Jarvik 2000, has received CE mark approval in Europe, has completed a 63 patient Pilot IDE study, and enrolled 100 of 150 patients in the IDE pivotal bridge to transplant study. The company thus has sufficient experience to sponsor an IDE clinical trial of the infant Jarvik 2000 and to obtain HUD designation and HDE approval. Over the course of the present five year contract we have collaborated successfully with Dr. Griffith's animal laboratory at the University of Maryland, and they will be a major subcontractor if our proposal is funded. Dr. Bartley Griffith, the Co-PI together with Dr. Jarvik, has extensive cardiac surgical experience with numerous mechanical circulatory support devices, and is a pediatric cardiac surgeon as well as an adult surgeon. We have established relationships with major pediatric cardiac surgical centers that have expressed interest in joining an multi-center Clinical Trial to evaluate the pediatric Jarvik2000. These include Dr. William Gaynor (University of Pennsylvania), Dr. Pedro del Nido (Boston Children's Hospital), Dr. Richard Jonas (Washington National Pediatric Center), Dr. Ed Bovie (University of Michigan) and Dr. Marcelo Cardarelli, Dr. Duke Cameron, and Dr. Luca Vricella (University of Maryland & Johns Hopkins). The PIs from each site will comprise an advisory group for the development of our IDE application, and will advise us concerning other clinical matters including surgical technique and patient management.